To prevent food poisoning after ingesting sea snails containing tetramine we measured the tetramine $[(CH_3){_4}N^+]$ contents of sea snails from the Korean coast using both ion chromatography (IC) and spectrometry. In total, 177 sea snails were collected from the east (Pohang, 19 species, 95 individuals), the west (Gunsan, 4 species, 46 individuals), and the south (Tongyeong, 8 species, 36 individuals) coasts. The working solution of tetramine standard for IC and the tetramine extract from the salivary gland of Neptunea arthritica cumingii were very stable for one month at $18^{circ}C,;4^{circ}C$, and room temperature. The tetramine content was high in the salivary gland of Heptunea species such as N. intersculpta $(9,813{mu}g/g)$, N. arthritica $(8,240{mu}g/g)$, N. arthritica cumingii $(6,967{mu}g/g)$, N. eulimata $(6,946{mu}g/g)$, N. constricta $(5,965{mu}g/g)$, and N, amianta $(4,502{mu}g/g)$. The mid-gut gland and muscle contained small amounts of tetramine. The tetramine content was highest in the autumn, but no clear regional variations were observed.